[18F]Fluorodeoxyglucose PET/CT and prediction of histopathological response to neoadjuvant chemotherapy for adenocarcinoma of the oesophagus and oesophagogastric junction

Prognostic value of [18F]FDG PET/CT on treatment response and progression-free survival of gastroesophageal cancer patients undergoing perioperative FLOT chemotherapy

PURPOSE

To evaluate the prognostic role of [¹⁸F]FDG PET/CT metabolic parameters in gastric cancer (GC) and gastroesophageal adenocarcinoma (GEJAC) patients receiving neoadjuvant chemotherapy.

METHOD

In this retrospective study, 31 patients with biopsy-proven GC or GEJAC were included between August 2016 and March 2020. [¹⁸F]FDG PET/CT was performed before the neoadjuvant chemotherapy. Primary tumours' semi-quantitative metabolic parameters were extracted. All patients received a perioperative FLOT regimen thereafter. Post-chemotherapy [¹⁸F]FDG PET/CT was performed in most patients (17/31). All patients underwent surgical resection. Histopathology response to treatment and progression-free survival (PFS) were evaluated. Two-sided p-values < 0.05 were considered statistically significant.

RESULTS

Thirty-one patients (mean age = 62 ± 8), including 21 GC and 10 GEJAC patients, were evaluated. 20/31(65%) patients were histopathology responders to neoadjuvant chemotherapy, including twelve complete and eight partial responders. During the median follow-up of 42.0 months, nine patients experienced recurrence. The median PFS was 60(95% CI:32.9-87.1) months. Pre-neoadjuvant chemotherapy SULpeak was significantly correlated with pathological response to treatment (p-value = 0.03;odds ratio = 16.75). In survival analysis, SUVmax (p-value = 0.01;hazard ratio[HR] = 1.55), SUVmean (p-value = 0.04;HR = 2.73), SULpeak (p-value < 0.001;HR = 1.91) and SULmean (p-value = 0.04;HR = 4.22) in the post-neoadjuvant chemotherapy pre-operative [¹⁸F]FDG PET/CT showed significant correlation with PFS. Additionally, aspects of staging were significantly correlated with PFS (p-value = 0.01;HR = 2.21).

CONCLUSIONS

Pre-neoadjuvant chemotherapy [¹⁸F]FDG PET/CT parameters, especially SULpeak, could predict the pathological response to treatment in GC and GEJAC patients. Additionally, in survival analysis, post-chemotherapy metabolic parameters significantly correlated with PFS. Thus, performing [¹⁸F]FDG PET/CT before chemotherapy may help to identify patients at risk for inadequate response to perioperative FLOT and, after chemotherapy, may predict clinical outcomes.

PET/CT-tailored treatment of locally advanced oesophago-gastric junction adenocarcinoma: a report on the feasibility of the multicenter GastroPET study

BACKGROUND

Perioperative chemotherapy is a recommended treatment approach for localised oesophago-gastric junction adenocarcinoma, but not all patients respond to neoadjuvant chemotherapy. Early identification of non-responders and treatment adaptation in the preoperative period could improve outcomes. GastroPET is a national, multicentre phase II trial evaluating a 18FDG-PET/CT-guided preoperative treatment strategy with the R0 resection rate as a primary endpoint. Here, we report on the accuracy of the methodology, the feasibility of the study design and patient safety data after enrolment of the first 63 patients.

METHODS

Patients with locally advanced oesophago-gastric junction adenocarcinoma (Siewert I - III) stage Ib-IIIc underwent baseline 18FDG-PET/CT scanning and re-evaluation after 14 days of oxaliplatinum-5FU-(docetaxel) chemotherapy. Responders were defined by a ⩾ 35% decrease in tumour FDG standardised uptake value (SUV)average from baseline. Responders continued with the same chemotherapy for 2 to 3 months prior to surgery. PET-non-responders switched to preoperative chemoradiotherapy [weekly carboplatin and paclitaxel with concurrent radiotherapy (45 Gy in 25 fractions)]. Here, we aim to confirm the feasibility of FDG-PET-based response assessment in a multicenter setting and to compare local versus central reading. In addition, we report on the feasibility of the study conduct and patient safety data.

RESULTS

A total of 64 patients received baseline and sequential 14-day 18FDG-PET/CT scanning. And, 63 were allocated to the respective treatment arm according to PET-response [35 (56%) responders and 28 (44%) non-responders]. The concordance of local versus central reading of SUV changes was 100%. Until the date of this analysis, 47 patients (28 responders and 19 non-responders) completed surgery. Postoperative complications of grade ⩾ 3 (Common Terminology Criteria for Adverse Events, CTCAE Version 5.0) were reported in five responders (18%; 95% CI: 7.9-36%) and two non-responders (11%; 95% CI: 2.9-31%), with no statistical difference (p = 0.685). One patient in each arm died after surgery, leading to a postoperative in-hospital mortality rate of 4.3% (2/47 patients; 95% CI: 1.2-14%).

CONCLUSION

Local and central FDG-SUV quantification and PET-response assessment showed high concordance. This confirms the accuracy of a PET-response-guided treatment algorithm for locally advanced oesophago-gastric junction cancer in a multicenter setting. Preoperative treatment adaptation revealed feasible and safe for patients.

Metabolic activity by FDG-PET/CT after neoadjuvant chemotherapy in borderline resectable and locally advanced pancreatic cancer and association with survival

BACKGROUND

The optimal prognostic markers for neoadjuvant chemotherapy in patients with borderline resectable or locally advanced pancreatic cancer are not yet established.

METHOD

Patients who received neoadjuvant chemotherapy prior to surgery and underwent FDG-PET/CT between July 2012 and December 2017 were included. Metabolic parameters including standardised uptake value (SUV), metabolic tumour volume (MTV), and total lesion glycolysis (TLG) on PET/CT, and response evaluations using PERCIST criteria, were investigated for its impact on survival and recurrence. Cox proportional hazards model was performed. Differences in risk were expressed as hazard ratio [HR] with 95% confidence interval [c.i.].

RESULTS

The patients with borderline resectable (N = 106) or locally advanced pancreatic cancer (N = 82) were identified. The median survival was 33.6 months. Decreased metabolic parameters of PET/CT after neoadjuvant chemotherapy were associated with positive impacts on survival and recurrence such as SUVmax (HR 1.16, 95% c.i. 1.01 to 1.32, P = 0.025), SUVpeak (HR 1.26, 95% c.i. 1.05 to 1.51, P = 0.011), and MTV (HR 1.15, 95% c.i. 1.04 to 1.26, P = 0.005). Large delta values were related to a positive impact on recurrence such as SUVmax (HR 1.21, 95% c.i. 1.06 to 1.38, P = 0.005). Post-neoadjuvant chemotherapy SUVmax ≥3 (HR 3.46, 95% c.i. 1.21 to 9.91; P = 0.036) was an independent prognostic factor for negative impact on survival. Patients with post-neoadjuvant chemotherapy SUVmax <3 showed more chemotherapy cycles (8.7 versus 6.2, P = 0.001), more frequent complete metabolic response (25 vs 2.2%, P = 0.002), smaller tumour size (2.1 vs 3.1 cm, P = 0.002), and less frequent lymphovascular invasion (23.7 vs 51.1%, P = 0.020) than patients with SUVmax ≥3.

CONCLUSION

Reduction in metabolic tumour parameters of FDG- PET/CT after neoadjuvant chemotherapy indicates improved overall survival and recurrence-free survival.

Response rate and diagnostic accuracy of early PET-CT during neo-adjuvant therapies in oesophageal adenocarcinoma: A systematic review and meta-analysis

PURPOSE

Only 25% of oesophageal adenocarcinoma (OAC) patients have a pathological response to neo-adjuvant therapy (NAT) before oesophagectomy. Early response assessment using PET imaging may help guide management of these patients. We performed a systematic review and meta-analysis to synthesise the evidence detailing response rate and diagnostic accuracy of early PET-CT assessment.

METHODS

We systematically searched several databases including MEDLINE and Embase. Studies with mixed cohorts of histology, tumour location and a repeat PET-CT assessment after more than one cycle of NAT were excluded. Reference standard was pathological response defined by Becker or Mandard classifications. Primary outcome was metabolic response rate after one cycle of NAT defined by a reduction in maximum standardised uptake value (SUVmax) of 35%. Secondary outcome was diagnostic accuracy of treatment response prediction, defined as the sensitivity and specificity of early PET-CT using this threshold. Quality of evidence was also assessed. Random-effects meta-analysis pooled response rates and diagnostic accuracy. This study was registered with PROSPERO (CRD42019147034).

RESULTS

Overall, 1341 articles were screened, and 6 studies were eligible for analysis. These studies reported data for 518 patients (aged 27-78 years; 452 [87.3%] were men) between 2005 and 2020. Pooled sensitivity of early metabolic response to predict pathological response was 77.2% (95% CI 53.2%-100%). Significant heterogeneity existed between studies (I²  = 80.6% (95% CI 38.9%-93.8%), P = .006). Pooled specificity was 75.0% (95% CI 68.2%-82.5%), however, no significant heterogeneity between studies existed (I²  = 0.0% (95% CI 0.0%-67.4%), P = .73).

CONCLUSION

High-quality evidence is lacking, and few studies met the inclusion criteria of this systematic review. The sensitivity of PET using a SUVmax reduction threshold of 35% was suboptimal and varied widely. However, specificity was consistent across studies with a pooled value of 75.0%, suggesting early PET assessment is a better predictor of treatment resistance than of pathological response. Further research is required to define optimal PET-guided treatment decisions in OAC.

Predicting tumor response and prognosis to neoadjuvant chemotherapy in esophageal squamous cell carcinoma patients using PERCIST: a multicenter study in Japan

PURPOSE

To investigate the usefulness of the positron emission tomography response criteria in solid tumors 1.0 (PERCIST1.0) for predicting tumor response to neoadjuvant chemotherapy and prognosis and determine whether PERCIST improvements are necessary for esophageal squamous cell carcinoma (ESCC) patients.

PATIENTS AND METHODS

We analyzed the cases of 177 ESCC patients and examined the association between PERCIST and their pathological responses. Associations of whole-PERCIST with progression-free survival (PFS) and overall survival (OS) were evaluated by a Kaplan-Meier analysis and Cox proportional hazards model. To investigate potential PERCIST improvements, we used the survival tree technique to understand patients' prognoses.

RESULTS

There were significant correlations between the pathologic response and PERCIST of primary tumor (p < 0.001). The optimal cutoff value of the primary tumors' SULpeak response to classify pathologic responses was -50.0%. The diagnostic accuracy of SULpeak response was 87.3% sensitivity, 54.1% specificity, 68.9% accuracy, positive predictive value 60.5%, and negative predictive value 84.1%. Whole-PERCIST was significantly associated with PFS and OS. The survival tree results indicated that a high reduction of the whole SULpeak response was significantly correlated with the patients' prognoses. The cutoff values for the separation of prognoses were - 52.5 for PFS and - 47.1% for OS.

CONCLUSION

PERCIST1.0 can help predict tumor responses and prognoses. However, ¹⁸F-FDG-PET/CT tends to underestimate residual tumors in histopathological response evaluations. Modified PERCIST, in which the partial metabolic response is further classified by the SULpeak response (-50%), might be more appropriate than PERCIST1.0 for evaluating tumor responses and stratifying high-risk patients for recurrence and poor prognosis.